SetScrollInfo function

The SetScrollInfo function sets the parameters of a scroll bar, including the minimum and maximum scrolling positions, the page size, and the position of the scroll box (thumb). The function also redraws the scroll bar, if requested.

Syntax

Parameters

Handle to a scroll bar control or a window with a standard scroll bar, depending on the value of the
fnBar parameter.

fnBar [in]

Type: int

Specifies the type of scroll bar for which to set parameters. This parameter can be one of the following values.

Value

Meaning

SB_CTL

Sets the parameters of a scroll bar control. The
hwnd parameter must be the handle to the scroll bar control.

SB_HORZ

Sets the parameters of the window's standard horizontal scroll bar.

SB_VERT

Sets the parameters of the window's standard vertical scroll bar.

lpsi [in]

Type: LPCSCROLLINFO

Pointer to a SCROLLINFO structure. Before calling SetScrollInfo, set the
cbSize member of the structure to
sizeof(SCROLLINFO), set the
fMask member to indicate the parameters to set, and specify the new parameter values in the appropriate members.

The
fMask member can be one or more of the following values.

Value

Meaning

SIF_DISABLENOSCROLL

Disables the scroll bar instead of removing it, if the scroll bar's new parameters make the scroll bar unnecessary.

SIF_PAGE

Sets the scroll page to the value specified in the
nPage member of the SCROLLINFO structure pointed to by
lpsi.

SIF_POS

Sets the scroll position to the value specified in the
nPos member of the SCROLLINFO structure pointed to by lpsi.

SIF_RANGE

Sets the scroll range to the value specified in the
nMin and
nMax members of the SCROLLINFO structure pointed to by
lpsi.

Specifies whether the scroll bar is redrawn to reflect the changes to the scroll bar. If this parameter is TRUE, the scroll bar is redrawn, otherwise, it is not redrawn.

Return value

Type: int

The return value is the current position of the scroll box.

Remarks

The SetScrollInfo function performs range checking on the values specified by the
nPage and
nPos members of the SCROLLINFO structure. The
nPage member must specify a value from 0 to
nMax -
nMin +1. The
nPos member must specify a value between
nMin and
nMax -
max(
nPage– 1, 0). If either value is beyond its range, the function sets it to a value that is just within the range.

If the fnBar parameter is SB_CTL and the window specified by the hwnd parameter is not a system scroll bar control, the system sends the SBM_SETSCROLLINFO message to the window to set scroll bar information (The system can optimize the message to SBM_SETPOS or SBM_SETRANGE if the request is solely for the position or range). This allows SetScrollInfo to operate on a custom control that mimics a scroll bar. If the window does not handle SBM_SETSCROLLINFO (or the optimized SBM_SETPOS message or SBM_SETRANGE message), then the SetScrollInfo function fails.